I agree with your rule, but I would add something extra:
Only build if you have the talent to do so. Early on Amazon managed to attract serious tech talent to the company. That enabled them to build. If a company can't do that then it's better to buy no matter what.
Only build if you have the talent to do so. Early on Amazon managed to attract serious tech talent to the company. That enabled them to build. If a company can't do that then it's better to buy no matter what.